Prefabricated staircase structure



March 21, 1967 R.'c. ROLLAND PREFABRICATED STAIRCASE STRUCTURE 2 Sheets-Sheet 1 Filed Jan. 21, 1964 March 2B, 1967 R. c. ROLLAND 3,310,132

PREFABRIGATED STAIRCASE STRUCTURE Filed Jan. 2l, 1964 2 Sheets-Sheet 2 Projecting laterally from the sides of the horizontal end Stringer sections a and b near their connections with the sloping Stringer Section c are smaller cradle members 16a and 1617 co-mprising hanged V-channels and adapted to receive and support joists 17a and 17b provided in the form of channel beams generally similar to the cradles 16a and 16h. The joists 17a, 17b have horizontal plates welded across their flanges to seal their upper surfaces and said plates project beyond the ends of the corresponding channels to take support on the cradle members 16a and 1Gb.

FIG. 2 illustrates a step member 7 about to be swung into position, as indicated by the arrows f1 and f2, in engagement with a slot 14 of the Stringer. The step member is a sheet metal element including a substantially trapezoidal front part 1S, providing the rise of the step, extended laterally by two Stiener sidewalls 19 disposed lsymmetrically on either side of the step. The step member further includes a rectangular tread portion 20, which is concealed from view in FIG. 2, but is seen c g. in FIG. 3. Each step member has associated with it a supporting base-block 21, comprising welded bent metal sheeting in the general form of a box, with a hook-like strip 22 projecting forward and downward from its rear end. The transverse cross sectional contour of the block 21 is complementary t-o that of channel 11a.

Referring to FIG. 3, it will be observed that the channels 11 and 11n of the cradle member 8a `and the Stringer end Section a differ from each other only in that the web of the channel 11a of the Stringer is positioned somewhat higher than the web of the channel 11, so as to permit the former to overlie the latter, as is visible in the right part of the figure. This figure clearly illustrates the attachment of each of the steps 7 over the Stringer. It is Seen that the hook 22 at the rear of the base block 21 of each step 7 is engaged in a slot 14 of the Stringer web 11a, and that the under surface of the bottom sheet element of said base block bears upon the upper side of said web. The tread portions Ztl of the steps are provided with facing plates Ztia which may be made of any desired rnaterial, e.g. wood or plastic. Shown in dotted outline in relation to the topmost Step is the lposition of the Step as its hook 22 is inserted through the corresponding uppermost slot 14 of the Stringer and just prior to the step being lowered into its iinal position, as indicated by the arrows f3. The manner of attachment of the step to the Stringer will be returned to in greater detail later.

The upper horizontal end section a of the Stringer is seen to Support a facing slab forming part of the floor 5, and including a base block at its under face, engageable into the recess of channel 11a, so as to t therein.

AS shown in FIG. 4, the Shallow channels 11 and 11a of the cradle and horizontal Stringer section are secured in their interftted position by irneans of threaded rods 23 inserted through the registering holes 13 and 13a, and blocked in position by means of nuts 25 threaded on the rod and acting outwardly on washers 24 having slanting -outer faces to fit the slope of the side flanges of the channel sections.

The construction of a step member 7 will now be described in greater detail with reference to FIGS. and 6. The step member is formed from a blank of sheet metal which includes a rectangular ypart and a trapezoidal part 18 the longer parallel side de of which is common to the rectangle as a longer side of the latter. This common side de constitutes one of the fold lines about which the blank is bent to constitute the finished step. The trapezoidal part 18 which, as earlier indicated and as will be clear lfrom FIG. l, provides the rise of the step, is defined by the above-mentioned fold line de providing its longer parallel side, a parallel fold line fg providing the shorter parallel side of the trapezoidal, and two symmetrical oblique fold lines ef and gd. From these two lines there extend a -pair of trapezoidal side flaps 19, which constitute the sidewalls 19 of the Steps previously referred to. It will be seen that when the blank is bent along the fold lines de, ef, gd in the manner shown in FIG. 6, the rectangular part 20 constitutes the ap upper tread Of the Step, the trap-ezoid 18 constitutes the rise, and the fla-p 19 constitute said sidewall. The edges en and me are of equal length and are adapted to be welded together in the fully bent condition of the step and the same is done symmetrically on the opposite side of the step. The small lower rectangle fgkl is bent to provide a Shelf directed forwardly at the bottom of the riser and on which the rear edge of the tread of the immediate lower step is adapted to be rested So as to be held in the angle enclosed by such shelf and the contiguous riser, as will appear from FIG. 3. The arrows f4 and f5 in FIG. 6 indicate the directions of the bending operations. A pair of holes 26 may be formed in the rectangular tread -portion 20 for convenience in handling and mounting operations. The resulting step member is lightweight yet very rigid and easy to mount in position. It is equally easy and cheap to make in large quantities, and can be surface treated in any desired manner in the factory for permanent protection.

The procedure used for erecting a flight of stairs, as shown in FIG. l, will be now described in detail.

After the cradle members 8a and 8b have first been assembled to the columns 1a and 1b so as to face each other at the respective floors, the Stringer is presented so that its horizontal end Sections a and b overlie the respective cradles, and is then eased as indicated by the arrows f6 in FIG. 2 until the projecting ends of its channel sections 11a drop into the corresponding recesses in the cradles. It will be noted that these operations are much facilitated by the light weight of the Stringer coupled to its high rigidity and Strength, a result of the cross Sectional shape of the Stringer including the deep V-channel 9 and the shallow U-channel 11a, assembled as described to provide a kind of box girder. If desired, plates of yielding plastic material may be interposed between the contacting surfaces to take up thermal expansions and prevent transmission of vibrations.

With the Stringer in place, the floor joist 17b may he mounted in a somewhat Similar fashion, by fitting one of its ends into the cradle member 16b and its opposite end into another cradle member, not shown, projecting from a Suitable joist or beam of the Structure. Over the joist 17b thus mounted and other joists or beams mounted at the Same level upon the columns, a ooring slab can then be placed, as by fitting base blocks of the floor slabs, similar to the base blocks 21 of the step members, into channel sections such as 11a of the joists. The positioning of one or more Hoor slabs in this way greatly facilitates subsequent erecting operations without requiring scaffolding.

The steps of the staircase can now be mounted. For this purpose the base blocks 21 of the lowermost step member 7 is positioned in register with the U-channel 11a of the intermediate Stringer Section c, and the step member is then swung as indicated by arrow f7 (FIG. 3) until the end of its hook 22 presents itself in register with the lowermost slot 14 of the Stringer. The hook is inserted into the Slot with a few strokes of a mallet, as indicated by arrows f3, and the step is thus firmly secured across the Stringer, so that it can be trodden on to mount the next Step, and so on up the ight of stairs. It will be noted from FIG. 3 that the base block 21 of each Step member iS blocked in its mounted position by the projecting shoulder of the next higher step, engaging the rear end surface of the block. The rear surface of the base block of the topmost step is in turn blocked by a Similar projecting shoulder of the base block of the flooring slab. It can also be noted that the hook 22 extending from the rear of a base block, is positioned below the point of application of the pressure exerted by the step member on .the Stringer, thereby ensuring full stability for the step in use,

Thus, without having to provide any scaffolding, the erectors are able to reach the top of the Stringer, step by step, and then position a floor joist 17a in the manner earlier described followed by a Hoor Slab.

Finally the screw rods 23 are inserted through the holes 13 and 13b (FIG. 4) to block the ends of the Stringer in place. For this purpose the nuts 25 are first backed inwards towards the center of the rod, and the rod is inserted in slanted position (arrow f8) into the holes 13 and 13a until a washer has abutted the inner side wall of the channel; the rod is then tipped as indicated by arrow i9 to bring its other end opposite to the hole 13 on the opposite Side, and is inserted into the hole as shown by arrow f10. The two nuts 25 are then Screwed outwards until they press firmly by way of the washers against the side walls of the Stringer.

It will be apparent from the foregoing description that a staircase thus erected can easily be dismantled and reused elsewhere if desired. Such operations are facilitated by the light weight of the component parts of the staircase. The parts are thus both economical of material and of labour and time required for mounting operations. Further, the need for scaffolding iS eliminated or greatly reduced.

Referring to FIG. 5, it will be noted that the blank of a step member can be cut out of a simple rectangular sheet element (shown dotted) with very little loss of material and is susceptible of cheap large-Scale manufacture. The fully shaped and erected steps, as Shown in FIG. 1, are extremely advantageous from the standpoints of economy, rigidity, and convenience, while being attractive in aspect. They may be used as erected, -or lined with any desired facing material, including wood, marble slab, plastics, etc.

The base block 21 may be attached to Steps members of various forms.

Various changes may be made in the illustrated embodiment within the scope of the invention. Thus in the case of a broad Staircase, two or more stringers may be used. The steps may then comprise pairs of step members each Similar to the member 7 described, mounted side by side. Alternatively, there may be provided step members having a tread part of increased length with two (or more) spaced base blocks 21 attached in it and provided with hooks 22 engageable with Slots formed in the related stringers.

The stringers are not necessarily straight, but may be curved, enabling the construction of curved, including, winding, staircases.

The step members may be secured to the stringers through means other than the hook Shown. Thus, pins may be inserted through aligned holes formed in the base blocks andthe sidewalls of the Stringer channel, in a manner generally similar to that in which the Stringer ends are Secured to the cradle members by way of the aligned holes 13, 13b, with suitable means being provided for retaining the pins in position. The pins may, moreover, be provided with annular grooves and shoulders or the like to provide means for centering the base block relating to a step adjacent the one considered. As a further alternative, the relationship between the hooks and apertures may be reversed: thus the Stringer-may be provided with a longitudinal row of hooks engageable with slots provided in the base of each step.

The base block, instead of being Shaped to fit into the recess of a Stringer channelmay be conformed as an inverted U for example so as to straddle a complementary contour of the Stringer.

The various components of the improved staircase, including the stringers, Step members, cradles and base blocks may be made of various materials other than metallic, e.g. wood, concrete, and the like.

What I claim is:

1. A staircase comprising at least one Stringer and a plurality of prefabricated step members engageable from above with said Stringer at locations regularly spaced along Said Stringer and extending transversely with respect to the latter, and Stringer including an elongated channel member having downwardly converging Sides and a bottom web extending between said sides and having transversely elongated Slots in Said web at locations spaced apart along the Stringer, each of said step members including a base having downwardly converging sides engageable with said sides of the channel member to transversely locate the step member with respect to said Stringer when being lowered onto the latter, said base of each Step member further having a ilat-webbed hook extending from the bottom of said base and opening forwardly below the latter so as to be guided transversely into Step- Securing engagement with one of said slots by the interengagement of Said sides of the base and channel member when a step member is lowered onto the Stringer, and means on each Step member interlocking with the next lower step member on Said Stringer to prevent movement of Said next lower Step member in the direction for disengaging Said ilat-webbed hook from the slot of Said bottom web in which it is engaged.

2. A Staircase comprising at least one Stringer and a plurality of prefabricated step members engageable from above with Said Stringer at locations regularly spaced along Said Stringer and extending transversely with respect to the latter, said Stringer including a generally V- Shaped elongated outer channel member of sheet metal and a relatively shallow channel member also of Sheet metal nesting in the upper portion of said outer channel member and having downwardly converging sides and a bottom web therebetween having transversely extending slots at locations spaced apart along the Stringer, each 0f Said Step members including a sheet metal blank bent to form a riser at the front of the step member, a tread extending rearwardly from the top of Said riser and a forwardly directed Shelf at the bottom of the riser enclosing an angle with the latter, each step member further including a Sheet metal base having downwardly converging sides engageable with the Similarly converging Sides of said shallow channel member to transversely locate the step member with respect to the Stringer when being lowered onto the latter, Said base further having a fiat-webbed hook extending from the bottom thereof and opening forwardly below said bottom of the base to engage in one of Said Slots for securing the step member on the Stringer, said tread of each step member being dimensioned to engage, at its rearward edge, in Said angle of the next higher step member and thereby be interlocked with the latter So that each Step member iS held against movement in the direction for withdrawing its hook from the related Slot by the interlocking engagement of each step member with the next higher step member secured on Said Stringer.

References Cited bythe Examiner UNTED STATES PATENTS 1,766,316 6/1930 Vance 52-8 1,870,598 8/1932 Amann 52-184 2,796,158 6/1957 Miles 52-188 2,818,945 1/1958 Holzer 52-191 3,216,160 11/1965 Best 52-189 FOREIGN PATENTS 1,119,467 6 France.

3,724 1891 Great Britain. 29,471 1910 Great Britain. 912,428 1962 Great Britain.

99,335 1962 Norway.

FRANK L. ABBOTT, Primary Examiner.

RICHARD W. COOKE, J' R., Examiner. R. A. STENZEL, Assistant Examiner. 

1. A STAIRCASE COMPRISING AT LEAST ONE STRINGER AND A PLURALITY OF PREFABRICATED STEP MEMBERS ENGAGEABLE FROM ABOVE WITH SAID STRINGER AT LOCATIONS REGULARLY SPACED ALONG SAID STRINGER AND EXTENDING TRANSVERSELY WITH RESPECT TO THE LATTER, AND STRINGER INCLUDING AN ELONGATED CHANNEL MEMBER HAVING DOWNWARDLY CONVERGING SIDES AND A BOTTOM WEB EXTENDING BETWEEN SAID SIDES AND HAVING TRANSVERSELY ELONGATED SLOTS IN SAID WEB AT LOCATIONS SPACED APART ALONG THE STRINGER, EACH OF SAID STEP MEMBERS INCLUDING A BASE HAVING DOWNWARDLY CONVERGING SIDES ENGAGEABLE WITH SAID SIDES OF THE CHANNEL MEMBER TO TRANSVERSELY LOCATE THE STEP MEMBER WITH RESPECT TO SAID STRINGER WHEN BEING LOWERED ONTO THE LATTER, SAID BASE OF EACH STEP MEMBER FURTHER HAVING A FLAT-WEBBED HOOK EXTENDING FROM THE BOTTOM OF SAID BASE AND OPENING FORWARDLY BELOW THE LATTER SO AS TO BE GUIDED TRANSVERSELY INTO STEPSECURING ENGAGEMENT WITH ONE OF SAID SLOTS BY THE INTERENGAGEMENT OF SAID SIDES OF THE BASE AND CHANNEL MEMBER WHEN A STEP MEMBER IS LOWERED ONTO THE STRINGER, AND MEANS ON EACH STEP MEMBER INTERLOCKING WITH THE NEXT LOWER STEP MEMBER ON SAID STRINGER TO PREVENT MOVEMENT OF SAID NEXT LOWER STEP MEMBER IN THE DIRECTION FOR DISENGAGING SAID FLAT-WEBBED HOOK FROM THE SLOT OF SAID BOTTOM WEB IN WHICH IT IS ENGAGED. 